1. Field of the Invention
The present invention is directed generally to a stationary or portable diagnostic system or electroanalytical systems for analyzing preselected characteristics of a patient's blood and other fluids. More particularly the present invention is concerned with a portable diagnostic device or analytic instrument that includes a plurality of test modules for analyzing various body fluids of a patient, wherein the modules are coupled to a common display, printer, power supply, and communication ports. The portable diagnostic device interfaces and utilizes disposable cartridges, reagent diagnostic test strips, or other means to determine, for example, a patient's blood pH, pO.sub.2, pCO.sub.2, Na.sup.+, Ca.sup.++, K.sup.+, hematocrit, glucose and/or other parameters including oxygen saturation, coagulation or hemoglobin fractions. The modules may determine the parameters through a variety of methods such as electrochemical, electrical, optical, or mechanical analysis of a fluid biological sample extracted from the patient. The disposable cartridge may utilize a bank of sensors for the pertinent electroactive species to provide input in the form of analog electrical signals for the relevant determinations.
II. Related Art
During clinical, surgical, diagnostic and other medical procedures the measurement of certain physical/chemical characteristics or conditions of the blood and other fluids of a patient are useful in order to evaluate the condition of a patient. For example, a patient's blood pH, pO.sub.2, pCO.sub.2, Na.sup.+, Ca.sup.++, K.sup.+, hematocrit, glucose and other parameters including oxygen saturation coagulation or hemoglobin fractions may be measured. These conditions may provide important indications of the patient's stability including, for example, the efficiency of the blood/gas exchange occurring in the lungs of the patient, the relative acid/base balance, or the concentration of certain indicative ion species in the blood. Such determinations are particularly useful in emergency circumstances.
In the past, the equipment provided to make such determinations has typically been complex and permanently installed in a hospital laboratory. Also, the user operating the equipment has been oftentimes required to be a highly-trained and skilled technician, which thereby increases the cost of operating the equipment and limits the number of potential users. With such equipment, in order to analyze a sample of fluid from the patient, a sample must be drawn from the patient and delivered to the laboratory, avoiding all external contacts.
During the transfer and delivery, the drawn fluids may be kept in close proximity to ice packs in order to maintain sample integrity. The sample is then injected into a designated receptacle of the diagnostic equipment and the equipment operated to perform the diagnostics on the sample. This procedure is time consuming, labor intensive, and usually disadvantageous in the operating room, emergency room or other area of the hospital, or outside the hospital where time is of the essence. Hence, portable devices that reduce the time required to make accurate blood-gas and related determinations, in order that proper and more timely corrective steps may be taken, are highly sought.
Many situations arise where it is impractical to deliver a patient's fluid sample to a hospital laboratory in order to analyze the patient's blood analytes. It would be desirable for paramedics and in-home health care providers, for example, to analyze a sample at the point of collection without having to first deliver a sample to a hospital laboratory. To this end, it would also be desirable to provide a single portable diagnostic device capable of analyzing simultaneously several samples and/or conducting several electrochemical, electrical, optical, or mechanical analysis simultaneously or in rapid succession to determine, a patient's blood pH, pO.sub.2, pCO.sub.2, Na.sup.+, Ca.sup.++, K.sup.+, hematocrit, glucose and other parameters including oxygen saturation, coagulation or hemoglobin fractions.
There have been attempts at point-of-care blood-gas analysis. One on-site analytic device, described by Enzer et al in U.S. Pat. No. 4,786,394, is designed for direct connection to a heart/lung machine to monitor critical blood gases during open-heart surgery. It employs a discardable sensor cartridge which contains a bank of sensors for making the electrochemical determinations. A further patent to Enzer et al (U.S. Pat. No. 4,397,725) also discloses a clinical blood chemistry analyzer in which a discardable cartridge interfaces with an analytical machine. Although the analyzer may be utilized on-site during surgery, the device disclosed by Enzer remains relatively stationary and immobile. Morris et al in U.S. Pat. No. 5,325,853 (of common assignment with the present invention) disclose a self-calibrating disposable sensor system.
Carter et al in U.S. Pat. No. 5,628,890 describe an electrochemical sensor for measuring the glucose concentration in a patient's blood. Such a sensor is limited to the particular analyte being measured and requires an interface with an electrochemical sensor. Stark in U.S. Pat. No. 5,433,197 describes a non-invasive glucose measurement device that requires illumination of the patient's eye with near infrared radiation. The capability of the Stark device is limited to determining blood glucose. Phillips et al in U.S. Pat. No. 5,563,042 describe a device that measures glucose concentration in whole blood optically using a reflective reading apparatus and a whole blood glucose test strip.
A further reference is contained in U.S. Pat. No. 4,849,340 to Oberhardt discloses a device that measures coagulation in whole blood using a liquid assay device and method.
Although somewhat useful, such devices are limited in application and address only part of the drawbacks of prior systems. There remains a need for a rapidly responding, portable blood chemistry analytical device. A need also exists for a single, portable, self-calibrating, instant activation, rapid response diagnostic device capable of simultaneous analysis of several samples and/or conducting several electrochemical, electrical, optical, or mechanical analysis simultaneously or in rapid succession to determine, blood pH, pO.sub.2, pCO.sub.2, Na.sup.+, Ca.sup.++, K.sup.+, hematocrit, glucose and other parameters including oxygen saturation, coagulation or hemoglobin fractions. The present invention meets these needs and overcomes the disadvantages of prior devices.